Starling Murmuration

A murmuration of thousands of starlings flies in formation near Henry Road on Monday morning.

J.L. Sousa, Register

What in the world are these birds doing?

Starlings by the thousands descend on Napa Valley vineyards in the winter season. They announce their presence by flying in astonishingly large, massed formations — called murmurations — that swirl this way and that.

The choreography is dazzling. Somehow they manage not to ricochet off each other, turning aerial ballets into chaos.

Starlings are known for their fallow-season swooping and diving in formations that can swell into the tens of thousands. They swoop by day in unobstructed area, then return to roosting sites at night.

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Observers say these large congregations can provide the birds safety from predators as they feed collectively, as well as warmth.